These are not big ones.

These are needed in *BSD family

 * incorrect-path-for-interpreter /usr/bin/env perl != /usr/bin/perl [usr/share/mysql/mysql-test/mariadb-stress-test.pl]
 * incorrect-path-for-interpreter /usr/bin/env perl != /usr/bin/perl [usr/share/mysql/mysql-test/mariadb-test-run.pl]

and these are needed to make sure that these packages get removed if they exist:

 * version-substvar-for-external-package Replaces ${source:Version} libmariadb-dev -> libmysqlclient-dev [debian/control:*]
 * version-substvar-for-external-package Replaces ${source:Version} libmariadb-dev -> libmysqld-dev [debian/control:*]
 * version-substvar-for-external-package Replaces ${source:Version} libmariadbd-dev -> libmariadbclient-dev [debian/control:*]